Viscosity index is an important characteristic of lubricants, especially hydrocarbon lubricants since it provides a measure of the extent to which the viscosity of the lubricant will vary with temperature. Normally, a high viscosity index, indicative of a relatively lower rate of change of viscosity with temperature, is desired in a lubricant because it will then be possible not only to predict the performance of the lubricant over a wider range of conditions but, in addition, the allowances which will have to be made for variations in lubricant properties will be smaller, so that the design characteristics of machinery can be optimized to a greater degree. It has long been known that the viscosity index (VI) of a hydrocarbon lubricant is related to its structure: paraffins have the highest viscosity indices and among the paraffins the more highly branched the paraffin is, the lower will be its viscosity index. For this reason, the more linear paraffinic lubricants have traditonally been preferred for their high viscosity index although the extent to which they may be employed in practical, commercial lubricants is limited by the fact that these same materials also tend to have high pour points, itself an undesirable feature. In practice, this has meant that a compromise must normally be found between the desirable attributes of high viscosity index and low pour point and generally the problem has found its practical solution in the use of dewaxed oils of paraffinic origin in which the linear and slightly branched paraffins have been removed by the dewaxing process but leaving sufficient of the slightly more highly branched paraffins to confer a high viscosity index without raising the pour point to unacceptable levels. Processes of this kind, however, require a base stock which possesses sufficient of the less highly branched paraffins but which is sufficiently free of the more highly branched paraffins, in order to confer the desired high viscosity index and low pour point. Base stocks of this kind may not always be available and some method must therefore be found for their manufacture. Such a method is provided by the present invention.